The Indonesian government and a Japanese consortium are unlikely to reach an agreement on the planned nationalization of an aluminum producer following months of tough negotiations over the amount of Japanese shares in the firm, sources said.

The sources said the Japanese shareholders are now considering bringing the case to the International Court of Arbitration if no consensus is reached. The contract of cooperation between Jakarta and the Japanese consortium was due to expire Thursday.

The sources said Wednesday it would be "difficult" to achieve fruitful results with just a day remaining.